Clock setting mechanism and circuit



H. MAE'RZ March 16, 1954 CLOCK SETTING MECHANISM AND CIRCUIT 2 Sheets-Sheet 1 Filed Feb. 20. 1948 March 16, 1954 H. MAERZ CLOCK SETTING MECHANISM AND CIRCUIT 2 Sheets-Sheet Filed Feb. 20, 1948 lNvENToR Y Henry Maef BY MQVMM ArroRNI-:YS

the conventional remote controlled electric periodic synchronization of the master clock, which will cause all the secondary clocks in the system immediately to correct their setting after the master clock is synchronized and which will permit such periodic correction of the secondary clocks without impairing the operation of the master clock in governing the correct reading of the secondary clocks.

According to the invention, a control equipment is provided comprising a master clock, a secondary clock hereinafter designated a pilot clock, a control transmission mechanically interconnecting said clocks and a control circuit governed by said control transmission, which circuit eilects operation both of said pilot clock and of the plurality of remote secondary clocks in the system.

'I'he control transmission includes a pair of gear trains driven respectively by the master clock and pilot clock and a pair of diierential switches controlled thereby and governing the circuit for actuating the pilot clock and the secondary clocks.

A transmission element displaced by the regular movement or by the manual setting of the master clock, as for instance by a knob on the minute arbor thereof, sets the dillerential switch into operative position and when the pilot clock has been advanced electrically and reaches conformity with the master clock, the diilerential switch wil1 have been restored to inoperative position.

Preferably two differential switches are provided, one for the minute correction and one for the hour correction, and the switches are connected in parallel so that either may control the system.

`In a preferred embodiment herein shown, the diil'erential switches each comprise a pair of gears, each pair being idly mounted on a separate axis. Each pair of gears has a pair of contacts associated therewith which will close when the master clock and pilot clock do not indicate the same time, thereby to close a circuit to deliver impulses to the motors of the pilot clock and the secondary clocks and thus to advance them until they are in conformity with the master clock, at which time said differential switch contacts will reopen and the impulses to the pilot clock and secondary clocks will cease.

The master clock preferably is driven by an independent power supply such as a dry cell so as to operate independently of the main power supply which actuates the pilot clock and secondary clocks, thereby ensuring continued operation of the master clock in case of power failure.

In a preferred embodiment, a conventional remote controlled synchronizer is incorporated in the master clock periodically to correct its timing in accordance with timing signals from a remote Source such as by wireless impulses from a control station. Also in the master clock is conventional mechanism to actuate the synchronizers in the secondary clocks, say l minutes after such setting of the master clock, thereby guarding against loss in time in the outermost secondary clocks that should fail to respond to all the short duration actuating impulses from the master clock.

AReferring now to the drawings in which are shown one or more of various possible embodiments of the several features of the invention,

Fig.,1 is a fragmentary front elevational view oi' the control equipment with parts broken away,

Fig. 2 is a side elevational view of said equipment partly in cross section,

Fig. 3 is a sectional View on a larger scale taken along line 3-3 of Fig. l,

Fig. 4 is a diagrammatic view of the control equipment including the control circuit, incorporated in a secondary clock system, and

Fig. 5 is a fragmentary view of another embodiment of the control circuit.

Referring now to the drawings, a conventional secondary clock system is provided comprising a plurality of secondary clocks S located in any suitable place on board a ship, train or plane. Illustratively the secondary clocks are each preferably driven in one-half minute steps by a reversing polarity impulse motor of the type fully described in my copending application Serial No. 696,591, filed September l2, 1946, now issued Patent No. 2,469,834, dated May 10, 1949.

A conventional master clock M is also provided, preferably having its own power supply (not shown) which may be a dry cell battery.

The master clock M and a secondary clock hereinafter designated as pilot clock P which together form part of the control equipment, are positioned on a control panel with the minute arbors I E and Il thereof respectively preferably vertically aligned, and extending laterally from said control panel.

Associated with the master clock M and the pilot clock P and interconnecting the two is the control transmission I0 which also forms part of the control equipment and which comprises a frame II mounted on the control panel over the master clock M and the pilot clock P and having a front panel I2 and a rear panel I3 aixed thereto inspaced relation by spacer bars I3.

Mounted on the frame II between the front and rear panels I2 and I3 are two identical gear trains I4 and I5 provided with a twelve to one reduction ratio and driven respectively by the minute arbors IB and I'I of the master clock M and the pilot clock P.

As the gear trains I4 and I5 are identical, only the former will be described in detail, corresponding parts of the latter having the same reference numerals primed.

Gear train I4 comprises an arbor 2I connected to minute arbor I6 of the master clock by coupling 23 and journalled at its rear end in a bearing opening 22 in rear panel I3. The front end of arbor 2| has an hour hand sleeve 24 idly mounted thereon and journalled in a bearing bushing 25 in front panel I2.

Aiiixed upon arbor 2I by set screw 32, near the rear end thereof between panels I 2 and I3 is a gear 29 having a pinion 3l rigid therewith. Pinion 3l meshes with a gear 33 mounted on an arbor 34 journalled in bearing openings 35 and 36 in the front and rear panels I2 and I3 respectively. Rigid with gear 33 is a pinion'sl afiixed to arbor 34 by set screw 38. Pinion 31 meshes with gear 39 which is aiiixed to sleeve 24, upon the reduced nose 4I at the forward end of which is aiiixed the hour hand 43. Y

Upon the reduced forward end 44 of arbor 2l protruding beyond sleeve 24 and clock face' 42 is mounted a knurled knob 41 which is retained securely against shoulder 45 of the arbor 2l by nut 48'threaded on the extremity 46 ofsaid arbor 2I. Knob 41 has a minute hand 49 aiiixed thereto.

The reduced portion 44 Aof arbor 2| of gear train I5 is not as long as that of arbor 2I as no knob 41 is provided. Instead a collar 41' is securely retained againstfshoulder 4151 by nut 43" and carries minute hand: 4S'.

Associated with both theY gear trainsV llt and |15 are the diiierential switches and. 52 controlling the setting of the minute and hour hands respectively of the secondary clocks and of the piloty clock.

As they diiierential switches 5|. and 52 are identical only the former will be described in detail, corresponding parts of the latter having thesame reference numerals primed.

As: clearly shown in Fig. 3, differentialV switch 5| comprises a stud 53 rigidly affixed tothe rear panel |3'by a screw 54 and"having'two-independently rotatable hubs 55 and; 55 idly mounted thereon andr comprising respectively identical gears 51 and 581 spaced from each other.

Clear 51 meshes withgear 29y oi gear train I4 and is driven thereby in a counterclockw-ise direc-v tion and gear 58 meshes with gear 29' of `gear train l5 and? is also driven in acounterclockwise direction.

Gear 51' of differential switch 52 meshes with pinion 31 of gear train I4 and is driven thereby ina clockwise direction and gear 58" of d-iiferential switch 52 mesheswith pinion 31 of gear train |5 and is also driven thereby in a clockwise direction.

It is` therefore apparent that gears 51 and 58 of differential switch 5| are driven respectively byY gears 25J` and 29 which control the movement of theminute-handsof the master and pilot clocks and gears 51' and 58 of diiferential switch 52 are-driven, respectively, by pinions 31 and 3'1" which control the movement of the hour hands of the master and pilot clocks.

Gear 51 has a rivetl 59 therethrough and rigid therewith', provided with arounded heady 6 |V on its innerface Vin juxtaposition to gear 58. The latter has a cam stud |2v with a rounded head 6c extending, through an opening 63 therein and adapted to engage the head 6| of rivet 55 when the rivet and the stud are in registry.

The free end 65 of study 62 is afxe'dto the end of' a resilient contact arm 66 which is affixed at its free end in a mounting block 61 of insulating material secured to the face ofv gear- 58 by screws 68,Y said contact arm 65 being insulated from said gear.

VAlso affixed in mounting block 61 between contact' arm 66 and the gear 58, and in electrical contact with the latter, is a contact arm 69 carrying a contact4 1| atY one end in registry with, a corre,- sponding contact 12 on contact arm 66 and spaced therefrom when stud 62 'is in engagement with rivet 59.

Also carried on mounting block 61 in contact with. contact arm 6.6 is a resilient contact arm 13 carrying a contact 14 at one end` thereof axially aligned with stud 53 and which is in engagement with acontact 1'5 carried by an arm 16 afxed to front panel' I3 by screws 11, the two contacts 11| and 1'5 providing a rotating connection.

TheY master clock, pilot clock and control transmission above -described have associated therewith acontrol circuit which includes a plurality of .relays and associated elements to be hereinafter described and which also forms party of the control equipment.

Control, cir-cuit connected in parallel as` shown in Fig. '4. Thus contactsf 1|= andv 'H' vare connected. through. nxed.

6. Contact arms 691 and 65|.k on gears 5a and 58?, respectively, and the frame I the latter being connected from terminal 8| thereon to negative. mainv N by leads ill and 19. Contacts 12; and 12 are connected through contact arms 65 and 66", re.- spectively, contact arms 13 and 1.3', respectively, contacts 14 and 14.', respectively, contacts 15 and 15' respectively, arms 16, 16', respectively', andv lead 8.2 connecting said 'arms 1e and 16'. Arm 16 is connected by lead 33 to one end of the coil 80 of the control relay R-I, the other emitv of which is connected by leads 84 and 85 to fuse 8by and thence by lead 81 to positive main P.

A time delay circuit is provided for relay R-I comprising resistor 88 and condenser 89, connected in parallel thereacross by leads 9| and 92. This circ-uit functions to keep relay R-I energized for the reason hereinafterl set forth.

Relay R-I which is of` the single pole double vthrow type has .a pair of fixedcontacts 93 and 94 and al movable contact arm 95 connected at one end to the coil 30 by lead 54 and to positive main P through lead lli, fuse 86 and lead 51. Contact 93 is connected by lead 96 to the movable contact arm 91l of synchronization relay llt-2 which isV of. the single pole single throw type, and also to one end of' the coil 93 of relay R-Z. The other end of the coil 9,8 is. connected by lead 99 to one terminal IIlI of the synchronization switch |02, the

other terminal |03 of which isV connectedby leads4 |04 and 19 to negative main rl.A

Fixed contact |65 of relay R-2 is connected by lead |66 to one side of the coil I I I of the synchronization mechanism in each of the secondary clocks S of which three are illustratively shown. As such synchronization mechanism forms per se no part oi this invention, it will not be described in detail, being diagrammatically represented by coil I II.

Fixed Contact 94 of relay R-I is connected by lead II2 to common contact II3 of impulse relay R3 which is of the double pole double throw type, and thence by lead ||4 to one side of variable resistor II5, the other side of whichY is connected by lead IIS to one end of coil ||`1v of relay R-3.. The other end of coil ||1 is connectedto terminal H3: of an intermittent circuit interrupter H9, desirably of the thermal type, the other,` terminal I2 I' of which is connected by lead |22 and leads |23. and |24 to iixed' contacts |25 and |26, respectively, of relay R-3, and by leadsy |21 and 19 to negative main N'.

The circuit interrupter ||9 which is conventional in` construction and forms per se no part of this invention,illustrativelyis of the type comprising, a fixed contact arm |28 connected to terminal ||8 and having a contact |29 at the end' thereof in registry with a contact |3| at theA end of `movable contact arm |32, and normally in engagement therewith when no current is ilowing through the interruptor H9. Movable contact arm |32 is pivoted as at |33 and .a larnent wire |34. is looped. over the free end |35 thereof, thev filament wire being of such length when not conducting andV therefore cold, as` to keep contacts |29' and |3| together. One end ofthe filament wire isconnectedby leadV |36 to terminal |2I and thev other end is connected by lead |31 tothe movable contact arm L32. A coil spring- IBB. normally urging the contacts to open position aS- sures rapid opening of the latter without arcing when the filamenti is heated.

-It is Vof course tobe understood. that other types of` circuit interrupters` could be4 utilized herein,

the "oneshown. being merely a illustrative.k

Themovable contact arms |39 and |40 of relay Re3 move in unison, are insulated from each other and are associated, respectively, with contacts |26, ||3 and H3, |25. Contact arm |39 is connected by leads |4|, |42 to one side of coil |48 of the secondary clock motors and by leads |4| and |41 to one side of coil |48 of the pilot clock motor.

Contact arm |40 is connected by leads |49 and |50 to the other side of coil |48 and by leads |49 and |54 to the other side of coil |48.

The motors which have been diagrammatically represented by coils |48 and |48 are of the reversing polarity type requiring impulses for energization.

It is to be noted that lead |42 is common to both the synchronization coil and the motor coil |48 in the secondary clocks.

Operation Rotation of minute arbor 2| driven from arbor |6 of the master clock M rotates gear 29 and pinion 3| afiixed thereon. Pinion 3| through gear 33 on arbor 34 rotates pinion 31 which through gear 39 drives sleeve 24 with hour hand 43 affixed thereon.

As gear 29 rotates in a clockwise direction, it rotates gear 51 in counterclockwise direction on stud 53 and with it rivet head 6|, which moves out of engagement with the head 64 of stud 62. As rivet head 6| rides oil? stud 62, resilient arm 66 will move the latter inwardly into opening 63 in gear 58 to cause closure of normally open contacts 1| and 12.

It is to be noted that rivet head 6| does not have to move completely off stud 62 for contacts 1| and 12 to engage but even a slight movement of the rivet head down the curved head 64 of stud 62 is sufficient. Upon closure of contacts 1| and 12, a circuit will be completed to control relay R-I from negative main N, leads 19 and 19, terminal 8|, through the frame to fixed contact arm 69, contacts 1| and 12, movable contact arm 66, contact arm 13, contacts 14 and 15, arm 16, lead 83, through coil 89 of relay R-l, leads 84 and 85, fuse 86 and lead 81 to positive main P.

Energization of relay R-l will move movable contact arm 95 into engagement with fixed contact 94, thereby completing a circuit to impulse relay R-3. The circuit is from positive main P, lead 81, fuse 96, lead 85, contact arm 95, contact 94, lead ||2, common contact ||3, lead ||4, through variable resistor H5, lead I6, through the coil ||1 of relay R-3 to terminal ||8 of circuit interrupter ||9, fixed contact arm |28, normally closed contacts |29 and I 3|, lead |31, iilament |34, lead |36 to terminal |2|, leads |22, |21 and 19 to negative main N.

Energization of relay R-3 will move movable contact arms |39 and |40 thereof into engagement with fixed contacts ||3 and |25, respectively, thereby delivering an impulse to the coils |48 and |49 of the motors of the secondary clocks S and of the pilot clock P, respectively. The circuit is from positive main P, lead 81, fuse 86, lead 85, contact arm 95, contact 94, lead 2, contact H3, contact arm |39, leads |4| and |42, through coils |48 of secondary clocks S to lead |50 and in parallel therewith from lead 4| through lead |41 and the coil |48 of pilot clock P, to lead |54, said parallel circuit being completed by way of lead |49, through contact arm |40, fixed contact |25, leads |23, |21 and 19 to negative main N'.

The impulse delivered to the coils |48 and |48 o1' the motors of the secondary clocks and pilot clock will cause the amature ot their respective motors to rotate one step which `i1l1.is'

tratively is degrees, thereby rotating the minute arbor l1 of the pilot clock I9 and the corresponding arbors |5| of the various secondary clocks.

The gearing of the pilot clock and secondary clocks which are identical, for purposes of illustration will move the minute hands one-half minute at each impulse.

As the current flows through lament |34, it heats the latter causing it to expand, thereby enabling spring |38 to pivot arm |32, thus separating contacts 29 and |3I to break the circuit to the coil I1 of impulse relay R-3. Spring |50' thereof will thereupon move the arms |39 and |40 so that they respectively engage contacts |26 and I |3. This will reverse the polarity of the current to the coils |48 and |48 of the secondary clock motors and the pilot clock motor and deliver another impulse thereto.

With contacts |29 and 3| of circuit inter-` rupter I |9 separated, no current will pass through filament |34 and it will cool and contract, bringing contacts |29 and |3| into engagement to again energize coil ||1`of relay R-3 to cause an impulse again reversed in polarity to be delivered to coils |48 and |48.

By varying the resistance ||5, the amount of current flowing through the filament of circuit interrupter 9 can be controlled. The greater the current ow the shorter the period of time it will take the filament to heat up and hence the more rapid the rate of impulses delivered to the motors of the secondary clock S and the pilot clock P.

The circuit interrupter desirably has a frequency of from one to two times a second. The rate utilized depends upon the length of the lines and the number of secondary clocks in the system. Thus with long lines and many circuits, the voltage drop along the line may be such that if the impulses are rapidly transmitted, the individual impulses may not have suflicient force or long enough duration to actuate the more distant secondary clock motors. Thus the secondary clocks near the master clock would indicate the proper time while the more distant secondary clocks would be in error.

As arbor 2 I rotates under the drive from arbor |1 of the pilot clock at each impulse thereto, it will rotate the minute hand 49 and the hour hand 43. It will also rotate gear 29' and gear 58 in mesh therewith. This rotation of gear 68 will continue in intermittent steps withV each impulse until stud 62 engages rivet 59 and rides up the rounded head 6| thereof suiliciently to cam movable contact arm 66 away from contact arm 69 to separate contacts 1| and 12 so that the circuit to the control relay R-I will be broken and spring thereof will move movable contact arm 95 into engagement with contact 93.

'I'hus during normal operation of the clock system after each small advance of the minute hand of the master clock, the minute hands of the pilot clock and the secondary clocks will also move a. corresponding amount.

It is to be noted that although the hour hands of the pilot clock and the secondary clocks will also advance with each advance o1' their respective minute hands, this advance is so slight that rivet head 6| will not move sufficiently to cause stud 62' `to be displaced enough to cause contacts 1| and 12 to engage. Therefore the circuit controlled by said contacts 1I, 12'` will not be closed during normal operation of the system. However, as contacts 1|, 12 and 1I', 12' are in parallel, only one pair need close in order for the control circuit to be energized.

As the -circuit to the relays `and to the intermittent circuit interrupter IIS is broken except after each movement of the master clock, the current consumption of the system is a minimum.

As the contacts 1|, l2 may separate quickly during the impulse due to the rapid movement of thepilot clock, thereby deenergizing relay R-'I and preventing a complete impulse from reach-ing the secondary clock motors which would prevent rotation of the latter, it is desirable that rel-ay Rf-l remain energized for a short interval after the circuit thereto has been broken. To this end, the time delay circuit comprising resistor 88 and condenser 89 is provided, the condenser becoming charged when coil 80 is initially energized, and discharging through the resistance and coil 80 when the circuit through contacts 1|, 12 or 1|', 12' is interrupted to keep the coil energized for a vslight period of time thereafter. Thus, as contact arm 95 will remain against contact 94, the complete impulse from cir-cuit interrupter H will be delivered to the pilot and secondary clock motors.

Illustratively on each hour, the synchronizer (not shown) in the master clock is energized from some remote source and the minute hand of the master clock will be moved exactly to the hour indication, At say exactly a quarter after the hour, synchronization switch |02 is closed by the synchronization mechanism (not shown). Inasmuch as rivet 6| and stud 62 are so positioned with respect to each other that contacts '1| and 12 will not `engage until 15 seconds after Aa minute interval vor 15 seconds before a minute interval, the control relay R-l will not be energized at exactly the minute intervals and there will be no danger of the normal impulse and the synchronization impulse occurring at the same time. Thus, with synchronization switch |02 closed and relay Rf-I deenergized, contact arm 95 -of the latter will remain in engagement with fixed contact 93 to complete the circuit to synchronization relay R-2, the circuit being from positive main P, lead 81, fuse 86, lead 85, contact arm 5, contact 93, lead et, coil 98 of relay Rf-Z, lead Q9, contacts lol and |03 of synchronization switch H32, and leads |04 and 10 to negative main N. Movable contact gli will move into engagement with ixed contact |05, thus completing a circuit from positive main P, lead 81, fuse 86, lead 85, contact arm 9.5, contact s3, lead 96, contact `arm ell, contact H25, lead |05, through synchronization coil l! through common lead |42, lead 14|, .contact arm |39, contact |26, leads |24, |21 `and 'i9 to negative main N. Thus all the secondary clocks will be synchronized.

Up to this point the operation has been described with respect to the normal .driving and synchronizing' function of the system. If it is desired to `advance all the clocl-s in the system one hour, as would be necessary for example in a ship traveling from West to east every vtime it crossed a time zone, it is merely necessary to turn knob 48 of the master clock arbor 2| ,so that the hands thereof are advanced one hour. As arbor .2| .is connected to arbor I6 of the master clock and the latter is connected to vthe .gear train (not shown) in the ,master .clock by .a .conventional friction clutch (not shot/nh the gear movement in the master .clock will not be affected.

Rotation of the clock hands one hour willrestore the minute hand-to its original position with rivet `lil and stud B2 in engagement and contacts 1|, 12 separated. However, the hour hand will have been advanced and gear 39 will have rotated pinion 31, which in turn rotated gear El" in a clockwise direction, causing rivet 6| to move away from stud 62' permitting the latter to move into the opening in gear 58' to bring contacts l and l2 into engagement as previcusly described with respect to -contacts 1| and 12.

Closing of contacts ll and "|2 which are A.oonnected in parallel with contacts 'H and 1:2 will complete the circuit to the control relay Rf-I previously described, thereby delivering impulses :to the motors ci the pilot clock and secondary clocks to rotate the same. As it requires two impulses t0 the pilot clock vand secondary clock motors to rotate the hands thereof one minute, it will take impulses to advance the hands one hour and as the impulses are occurring at from one to :two times a second, it will take from one to two `minutes to set the clocks `ahead one hour.

Since by the arrangement above described, the synchronizer circuit is inactive whenever the differential switches or either of them is in operative position with the contacts thereof closed, there can be no interference with cr delay in .the return of the differential switches to inoperative position. Thus, in the absence of such arrangement, if the master clock should be advanced one hour, it would require 120 impulses to bring the secondary clocks in time therewith. If the minute hand should have advanced to say the 35 minute mark and a synchronization impulse should occur, the minute hands would be brought back to say the l5 minute mark and it would require 40 more impulses to restore the minute hand to its original position, thereby `slowing up the resetting operation. By reason of the interlocking feature of control relay Rf-l, this .diilculty is avoided. The synchronization impulse can only reach the secondary clocks when relay .Rf-l is deenergized and as the relay R-I will remain energized during the entire resetting 10eriod, no synchronization impulse lwill be delivered at such time.

inasmuch as the pilot clock is in close juxtaposition toits source of power, which vis controlled by the circuit interruptor, there is little or no danger of line losses which might interfere with the proper functioning of the pilot clock, and hence the latter will always be in time except in the case of power failure, and no synchronizer is required therefor, although one may be so provided if desired.

Although in the embodiment herein chosen :to illustrate my invention, a reversing polarity im# pulse motor is utilized in both the pilot clock and secondary clocks, it is within the scope .of this invention from its broader aspects to :utilize impulse motors that are not of the reversing polarity type or to utilize alternating current motors or direct current motors not of the impulse type.

In Fig. 5, the circuit of Fig. 4 is .shown modified to adapt it for use with .an impulse motor not of the reversing polarity type. 'To this .end the lead E23 need only be removed. Thus .as soon as relay R-l is venergized as heretofore described, an impulse will be delivered to the `motors .of the pilot clock and the secondary clocks, the circuit as shown in Fig. 5 being from positive main P, Ylead ,81, fuse Se, lead 85, contact arm-95, contact 29e, lead H2, contact |13, contact arm |40, lead M2, andleads |50 and |54 to onesiderofthe pilot clock motor, and through leads |42 and |41 from the other side of the motors, lead MI, contact 'arm |39, contact |26 and leads |24, |21 and 19 to negative main N.

The energization of relay R-I will also complete a circuit to circuit interrupter IIB from positive main P, lead 81, fuse 86, lead 85, contact arm 95, contact 94, lead H2, contact H3, lead H4, variable resistor H5, lead IIB, coil ||1 of relay R-3 to terminal I8 of the circuit interrupter ||9 and then from terminal |2| thereof, leads |22, |21 and 19 to negative main N.

Thus relay R-3 will be energized, moving contact arms |39 and |40 thereof away from contacts |26 and |13, respectively. As contact arm |40 will ybe in engagement with dead contact |25, the circuit to the motors will be broken.

It isapparent therefore that with each make and break of the circuit interrupter, one impulse will be delivered to actuate the pilot clock and secondary clock motors.

That this modied system shown in Fig. 5 could be`utilized to control alternating current or direct current motors in the pilot and secondary clocks is readily apparent. The making and breaking of the circuit thereto as above described would intermittently energize such motors to advance the hands of the clocks.

As many changes could be made in the above construction, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that lall matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. A control'equipment for a secondary clock system of the type comprising a master clock, a plurality of secondary clocks and a pilot clock. said secondary clocks and said pilot clock each aving an impulse motor; said equipment comprising a control transmission mechanically interconnecting said master clock and said pilot clock, said transmission comprising a pair of spaced parallel gears idly mounted on a common axle, said gears being driven by said master clock and said pilot clock respectively, a member xed on one of said gears and protruding from the inner face thereof, a movable member extending through the other of said gears and adapted to engage said fixed member when in registry therewith, a resilient arm having a contact thereon and carrying said movable mem- -beigand ailixed to and insulated from said last named gear, a contact arm aiixed to said last named gear and having a contact thereon in registry with the contact on said movable contact arm and normally spaced therefrom when said movable member Vand said fixed member are in engagement, said contact and said movable contact arm defining a switch, `a circuit interrupter controlled by said switch and connected in circuit with said impulse motors, whereby when said movable member and said xed member are moved out of engagement by movement of the gears of said pair of gears driven by said master clock, the switch will close to engage said circuit interrupter, for impulsing said impulse motors to move said pilot clock and secondary clocks into synchronization with said master clock.

2. A control equipment for a secondary clock systemsaid equipment comprising a frame, a gear train mounted on said frame, driving means for said gear train, a second gear train mounted on said frame having the same gear ratio as said ilrst gear train, driving means for said second gear train, each of said gear trains comprising a iirst arbor, a gear and pinion aiiixed on said rst arbor, a second arbor and a gear and pinion aiiixed on said second arbor, said last named gear meshing with said pinion on said first arbor, thereby rotating said pinion on said second arbor, a sleeve idly mounted on said first arbor, a gear rigid with said sleeve and meshing with the pinion on said second arbor, thereby rotating said sleeve, indicating hand aiiixed to said iirst arbor and said sleeve respectively, and rotated thereby, a pair of switches mounted on said frame, each of said switches comprising a pair of movable members, one of the movable members of each of said switches meshing respectively with the gear on said ilrst arbor of each of said gear trains and the other movable member of each of said switches meshing respectively with the pinion on said second arbor of each of said gear trains, and circuit means controlled by said switches to actuate said second driving means.

3. A control equipment for a secondary clock system, said equipment comprising a frame, a

gear train mounted on said frame, driving means` for said gear train, a second gear train mounted on said frame having the same gear ratio as said iirst gear train, driving means for said second gear train, each of said gear trains comprising a ilrst arbor, a gear and pinion affixed on said first arbor, a second arbor, a gear and pinion aillxed on said second arbor, said last named gear meshing with said pinion on said rst arbor, thereby rotating said pinion on said second arbor, a sleeve idly mounted on said rst arbor, a gear rigid with said sleeve and meshing with the pinion on said second arbor thereby rotating said sleeve, indicating hands aiiixed to said first arbor and said sleeve respectively, and rotated thereby, a pair of switches mounted on said frame, each of said switches comprising a pair of spaced, parallel gears, an axle aflixed to said frame and idly mounting said parallel gears so that they are movable with respect to each other, a member iixed on one of said gears protruding from the inner face thereof, a movable member extending through the other of said gears and adapted to engage said iixed member when in registry therewith, a resilient arm having a contact thereon and carrying said movable member and afiixed to and insulated from the other of said gears, a contact arm aiixed to said last named gear and having a contact thereon in registry with the contact on said movable contact arm and normally spaced therefrom when said movable member and said iixed member are in engagement, one of the gears o1' each of said switches meshing respectively with the gear on said rst arbor of each of said gear trains, and the other of said gears of each of said switches meshing respectively with the pinion on said second arbor of each of said gear trains, and circuit means controlled by said switches to actuate said second driving means.

4. A clock system comprising a master clock, a pilot clock having an impulse motor, a plurality of secondary clocks each having an impulse motor, normally open switch means controlled by said master clock and said pilot clock respectively. a control relay in series with said series with said impulse relay and said pair of 5 normally open contacts, said impulse relay being connected to deliver impulses of reverse polarity upon intermittent energization thereof, whereby when the closing of the switch of the master clock energizes said control relay to close its contacts, said impulse relay and said circuit breaker will be energized for intermittent energization of said impulse relay to deliver a plurality of impulses to said pilot clock and said secondary clock to actuate the latter.

5. The combination set forth in claim 4 in which said impulse relay is of the double pole double throw type connected to deliver impulses of reverse polarity at each position.

HENRY MAERZ.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Aron June 29, 1915 Poole July 15, 1919 Dicke Mar. 21, 1939 Holtz July 8, 1941 Maerz May 10, 1949 FOREIGN PATENTS Country Date Great Britain Apr. 23, 1914 Great Britain Dec. 24, 1914 Great Britain June 2, 1937 

